1. Field of the Invention
This invention relates to an improved printing blanket construction and to an improved method and apparatus for making a printing blanket construction.
2. Prior Art Statement
It is known to provide a printing blanket construction comprising an outer layer means formed mainly of polymeric material and having an outer printing surface means for carrying liquid printing ink means or the like for printing purposes or the like. For example, see the U.S. Pat. No. 1,778,185, to DeVries; the U.S. Pat. No. 3,025,186, to Eekhout et al; the U.S. Pat. No. 3,795,568, to Rhodarmer et al; the U.S. Pat. No. 3,881,045, to Strunk and the U.S. Pat. No. 4,015,046, to Pinkston et al.
It is also known that the structures of the outer printing surfaces of prior known printing blanket constructions have been controlled by grinding texture therein or by using a curing liner, such as paper, in combination with a dusting material, normally talc, disposed against the uncured surface and then being removed therefrom after the outer layer means has been cured. For example, see FIG. 6 of this application.
After applicants made their invention, applicants were informed through hearsay that it was believed that another utilized starch as the dusting material in combination with the curing liner perhaps on the basis that starch is a good release agent for subsequently removing the curing liner from the cured layer means. However, applicants have found that the starch can not be removed by normal washing of the outer surface of the cured blanket construction so that the printing surface with the non-removed starch provides inferior printing characteristics.
It is also known to provide raised structure, such as a plurality of projections, on the printing surface of a blanket composition to improve the ink carrying and/or paper release characteristics thereof. For example, see German Pat. No. 2,660,483 and pages 18-20 of the May 1983 issue of EPI.